Real and imaginary parts of complex permittivity of Aviation Turbine Kerosine (Hydro-fined) JetA-1 and Aviation Turbine Kerosine (Copper-Sweetened) JetA-1 are measured over the wide frequency range 8-12 GHz using X-band rectangular cavity resonator. The measurement technique uses the cavity perturbation technique. The fuel sample is filled in thin capillary tube of low loss material. It is then inserted through a sample hole at the centre of the broader side of the waveguide cavity resonator. The sample shifts the resonance frequency. The resonance frequency and shift in resonance frequency are measured using PNA Network Analyzer (AT E8362C). Validity of present measurement technique has been checked by measuring the dielectric properties of well-known dielectric materials (Plexiglas). Due to lack of experimental data in literature on dielectric parameters of Aviation fuels, it would be of great interest for the community to find its dielectric properties over wider frequency range. In addition the estimation of measurement error associated with this technique is also discussed.